Spike for motor vehicle tires



United States Patent SPIKE FOR MOTOR VEHICLE TIRES 11 Claims, 5 Drawing Figs.

U.S. Cl.

[51] Int.Cl. B60c 11/16 [50] Field ofSearch 152/210 [56] References Cited UNITED STATES PATENTS 2,982,325 5/1961 Pellaton 152/210 3,404,718 10/1968 Smith 152/210 Primary Examiner-Arthur L. La Point Attorney-Connolly and Hutz ABSTRACT: Spikes for motor vehicle tires, such as snow tires, are in the form of hard metal pins concentrically held by inwardly projecting ribs, reinforcing seams, or the like in synthetic casings.

SPIKE FOR MOTOR VEIIICLE TIRES BACKGROUND OF INVENTION The invention relates to a gripping pin for motor vehicle tires, in practice called a fspikef Such spikes are pressed into holes distributed overthe circumference of the tread of snow tires, in order to give thetires greater traction on ice and packed snow thus increasing the safety of motor vehicles equipped with such tires. The spikes consist generally of a hard metal pin protruding into the road surface. A holder or jacket whose foot is a widened plate or is disklike firmly and securely anchors each spike in the tire. The hard metal pin is fitted into the holder. or jacket in such a manner that it projects past its frontal surface by a margin to be effective in gripping. In this connection, in the spike fitted or shot into the tire tread, the frontal surface of the casing to the extent possible should terminate flush withthe tread surface, while the tip of the hard metal pin protrudes past this surface by l to 2 mm.

The development of snow tire spikes took a course form holders of aluminum, brass, bronze, and special steel to the presently most often used lead steel special alloy. The use of aluminum was discontinued since, during driving, the hard metal pin first positioned itself at an angle in the relatively soft holder, and was then further inclined by the forces exerted on a larger surface, whereby finally the entire spike itself worked its way out of the tire tread. Even the somewhat greater stability of brass and bronze could not solve the problem. Alloy steel was later employedbecause' it exhibits the required stability. Alloy steel, however, leads to a disadvantageous spark formation and noise trouble, particularly in driving on ice and snow-free streets. The main disadvantages, however, found in all metal holders and particularly in thoseconsisting of steel is the severe heatingwhich is transmitted directly to the tire rubber in the area of the spike and'which thereby leads to regeneration actions. A further disadvantage is the heavy weight of such spikes. It has therefore been attempted to abandon hard metal pins in favor of ceramic or porcelain spikes in order to utilize the hardness of this material, but this experiment had no success, since limited by the material, ceramic and porcelain spikes cannot be so shaped as to allow a secure and firm anchoring in the tire tread:

It has also been attempted to make the casing for'the spikes not of metal as is generally customary but of a synthetic material much closer related chemically and physically to the tire rubber than metaljso to speak akinto it, which in comparis'on to metal indeed has the disadvantage of the lower stability. Such material has a lineo'f advantages, however, among others the low heat conductivity considered to be essential, and therefore the advantage of not conducting the heat resulting in the driven tire in the hard metal pin, in a damaging manner to the rubber in the area of the spike. By a suitable selection of the synthetic material mixture and a glass fiber admixture, the heat conductivity can be further decreased and the stability increased, although not at the same rate. A further advantage is the almost complete avoidance of a noise problem, particularly in driving over iceand snow-free streets, and furthermore the lightweight, something which is specifically dealt with below.

In a motor vehicle tire the rionelastic mass should be as slight as possible. In this regard the spike with a synthetic material casing is-advantageous compared to entirely metal spikes because the nonelastic mass is decreased by more than 50 percent. This is a very important advantage, since if one pictures a single PKW tire equipped with about 100 spikes, one would realize that in each the an imbalance occurs which even by balancing the wheel cannot be entirely eliminated, and it would be taken into consideration that this imbalance constantly'changes because of the unavoidable unequal wear. Additionally, as aresult of the preferred asymmetric arrangement of the spikes in relation to the median plane through the tire eccentricities set in which are inaccessible to the balance of weight on the tire rim.

Despite these considerable advantages, however, previously spikes with synthetic material casings could not be carried through, since despite choosing special synthetic material mixtures and despite the glass fiber reinforcement, a sufficient stability could not be provided with certainty and particularly not because the firm anchoring of thehard metal pin in the casing was not always guaranteed. It occurred that the hard metal pins in the casing slackened, became loose, and sometimes even eventually fell out, or that the synthetic material, particularly at the frontal surface and in the proximity of the hard metal pins, was forced out upon considerable bending strain efiects in driving, or was melted away by the hard metal pin becoming very hot in driving on ice-- and snow-free streets. An alternative was attempted by means of a design where a hard metal pin was inserted into an aluminum holder and this was 'again encased with a synthetic material coating (German design Pat. No. 1,922,385). This: solution, however, can

eliminate neither the disadvantages of the spikes with pure metal holders nor those with synthetic material casing. For example, the aluminum casing contributes as a massive metal part to the heating of the spike and is a very good conductor which transmits the heat derived from the hard metal pin to the thin synthetic material casing. This thin synthetic material casing is not in a position to prevent the further transmission of heat to the surrounding rubber. A further disadvantage results from the high production costs, since first a so-called normal spike must be prepared'consisting of the hard metal pin and its aluminum casing, the conical hard metal pin being driven or pressed into the casing. The aluminum casing must be prepared in extrusion molding process. The synthetic material casing then cost-wise comes up to the costs of the spikes of the previous type. Of course there remains the disadvantage of the insufficient stability of the aluminum used as the casing with the already described result of the tilting of the hard metal pin in its casing and witbthe possibility of the working its way loose of the entire spike from the tire.

SUMMARY OF INVENTION The invention relates to a spike with synthetic material casing, which by maintaining the prescribed advantages avoids the above mentioned disadvantages, in that generally speaking the synthetic material is strengthened and hardened at the smallest possible weight increase, and the hard metal pin is centered in the casing by means of the hardening.

Accordingly, the invention relates to a spike for motor vehicle tires, consisting of a hard metal pin concentrically held in a synthetic material casing with anchoring foot, which is characterized in that a reinforcing jacket surrounding at a distance the hard metal pin is worked into the casing which centers the hard metal pin in the jacket 'by means of projections with ribs, reinforcing seams, side bars and the like directed inwards.

In a suitable embodiment, the reinforcing jacket is provided with holes, slots, and similar perforations.

The novel reinforcing jacket serves for the correct fixing of the hard metal pin both in the height as well as with respect to the exact centering. At the same time it forms in the synthetic 1 be broken up with a hammer, which. cannot be achieved with the spike according to the invention. A further considerable advantage achievable by means of the invention is that for the synthetic material used for the casing the glass fiber portion can be increased. The heat stability of the synthetic material is dependent on the amount of the glass fiber additive. However, while the heat stability with increasing glass fiber portion becomes considerably greater, at the same time the stability 3 decreases sharply. By the insertion of a reinforcing jacket,

which extensively takes care of the I maintenance of the required mechanical stability, the possibility occurs of raising theg'lass fiber content for the increase in thermal stability.

HE, DRAWINGS DESCRIPTION In FIG. 1 a spike is designated generally with 1, which con sists of a hard metal pin2 and a synthetic casing 3 having an anchoring disc 4. In order to guarantee a firm seating of the spike in the tread I of the tire. 102, (FIG. 5) stem 5 of the spike is drawn in at the transition to the anchoring disc 4 or in other words the stem is constructed of two superimposed frusto'cone sections seated base to base in such a manner that above the anchoring disc 4 there results a back taper. into which the rubber surrounding the spike can squeeze in driving into the treadof the'motor vehicle tire. In this conical transition area 7 of stern 5, hardening ribs 8 are arranged to the anchoririg plate 4, which onlthe one hand reinforce the cross section of the spike weakened at this point and on the other hand leave room for the insertion of the rubber of the tread surrounding the spike and holding it'by radial inward directed pressing. Ribs 8 support and reinforce therefore the anchoring plate that it cannottilt or become positioned at a slant to the stern.

According to the invention 'a frame in the shape of a jacket 9 is pulled into thesyntlietie material casing 3 which surcording to FIG. 1 in that the reinforcingjacket 14 is conically Q shaped, drawn over the hard metal pin 2 outwards in the in this manner to increase the friction contact between the rounds at a distance hard metal pin 2and also is situated at a ""distance from the outer surface of stem 5. By this frame the synthetic material cross section receives areinforcement with theres'ult that the stability of the casing is increased and the firm positioning of the hard metal pin in the casing is improved. s

The reinforcing jacket 9 is furthermore provided with inward directed reinforcing seams, grooves or indentations l0, whichflcent'er the hard metal pin in the casing and also fix it with respect to its proper height. The centering also simplifies the production of the spikelb y an injection molding machine. At the same time the centering prevents the falling out of the hard metal pin 2 from the casing 3 in that a thickening or enlarged foot or heading 1 1' of the end opposite the outer end of the hard metal pin leans against the inward projecting part 12 of the corrugation or like indentation 10, in case a loosening of the hard metal pin should still take place in the casing. Such a loosening however, is entirely or at least considerably avoided by using theinvention in that the jacket 9 acting as the reinforcing. frame holds together and reinforces the synthetic material especially injthe area of the hard metal pin.

Thereinforcing jacket 9, which in practice is about between 0.2 and 0.5 mmythick, in a suitable embodiment is equipped withperforations or apertures in the form'of holes and/or slots I3 through which the'syn'thetic material penetrates spraying around hard metal pin 2 for the formation of the casing, and

thus anchors the jacket in its tumin the casing. Thehard Imetal pin istli'erefo're surrounded in this embodiment not by two synthetic'rnat ei ial coatss'eparated by a reinforcing jacket but'ins'tead by one single homogeneous synthetic material coat in which the jacket i's 'i inbedded. Thus, a solid substance is providedwh'ose stability if sinc'reasedby the reinforcing jacket, whose chat or holder in extremeheat and mechanical stress is supported bya member and whose weight despite this is increasedjinnoticeably (e.g., 1.8 gr. in comparison to 3.8 grl in pure m etal spikes) as compared to a nonreinforced synthetic material casing.

direction to the anchoring plate or foot 4 and in this area 15 following about the incline of the transition area 7 between stem 5 and plate 4. Thereby even in this area the synthetic material casing is. reinforced and hardened. Furthermore, jacket 14 has at the height of the upper frontal surface 16 of the synthetic material casing further inward-directed projections 17, so that in the embodiment according to FIG. 2 the hard metal pin 2 is supported at top and bottom and is thus centered.

In the, embodiment according to FIGS. 3 and 4, which resembles that of FIG. 2, the inward-directed projections 18 and 19 centering the hard metal pin 2 in the synthetic material casing 3 and holding against movement in the direction of the arrow are soconstructed that they touch the hard metal pin not as in the embodiment according to FIGS. 1 and 2 only pointlike but instead with a larger surface 19a or 18a in order outer surface of pin 2 and the innersurface of jacket 20 and to anchor in the synthetic material casing 3 over the projection 21 reaching up to the root of the anchoring plate 4.

Of course the reinforcing jackets centering and holding the hard metal pin in the synthetic material casing instead of with inward-directed projections in the form of corrugations, grooves or like indentations can also be equipped with punched lugs or side bars connected along a bending edge with the jacket. If corrugations, grooves and like indentations are provided, they can proceed annularly about the entire circumference of the jacket or ata distance from .each other can be arranged on one or several horizontal planes displaced over each other or opposite each other.

Iclaim: e 1. A spike for motor vehicle tires comprising a casing made of a synthetic material an anchoring foot at the base of said casing, a reinforcing jacketembedded in said casing, a hard inetal pin in said jacket, and inwardly directed positioning means in said jacket centering said pin in said casing.

2. Aspike as set forth in claim 1 wherein apertures are in said jacket. I

3, A spike as set forth in claim 1 wherein said pin has an enlarged foot, and said positioning means including projections disposed above said foot.

4. Aspike as set forth in claim 3 wherein apertures are in saidjacket, said positioning means including further projections directed inwardly toward the portion of said casing remote from said anchoring foot.

5. A spike as set forth in claim 4wherein said jacket extends into said anchoring foot.

j 6. Aspike as set forth in claim 4 wherein said casing is in the form of a pair of frustoconical sections joined at their widened ends to provide an inwardly tapered transition section adjacent said anchoring foot, reinforcing ribs further joining said anchoring foot to. said transition section, and said jacket having an inwardly inclined portion at said transition section.

7. A spikeas set forth inclaim 1 wherein said positioning means includes projections directed inwardly toward the portion of said casing remote from said anchoring foot.

8. A spike as set forth in claim 1 wherein said jacket extends into said anchoring foot.

9. A spike as set forth inclaim 1 whereinsaid casing, includes a, transition region adjacent said anchoring foot, and said jacket extending into said transition section and being frustoconically shaped therein.

10. In amotor vehicletire having a tread surface, a spike mounted in said tire, the improvement being said spike comprising a casing made of a syntheticmaterial,,an anchoring foot at the base of said casing, a reinforcing jacket embedded in said casing, av hard metal pin in said jacket, inwardly directed positioning means in said jacket centering said pin in said casing, said casing being positioned in said tire flush with said tread surface, and said pin extending beyond said tread surface.

-joined at their widened ends to provide an inwardly tapered transition section adjacent said anchoring foot, reinforcing ribs further joining said anchoring foot to said transition section, and said jacket having an inwardly inclined portion at said transition section. 

